The present invention relates generally to ballistic resistant devices and systems and to methods of manufacture of such ballistic resistant devices and systems, and particularly, to ballistic resistant devices and systems for use in body armor and to methods of manufacture of such ballistic resistant devices and systems.
Ballistic resistant armor is used in many applications including, for example, protection of vehicles and persons from ballistic threats. Body armor to be worn on a person for protection from, for example, ballistic threats, has been available for several decades. In general, body armor protects vital parts of the human torso against penetration and severe blunt trauma from ballistic projectiles. In the development of body armor, there is a continuing effort to develop lighter, stronger, thinner, and more durable armor.
For example, monolithic and multi-component ceramic plates have been used in a number of hard body armors (that is, body armors including hard projectile resistant components or plates). See, for example, U.S. Pat. No. 6,253,655 and Canadian Patent No. 2,404,739. U.S. Pat. No. 6,253,655 discloses an armor including a durable spall cover for suppressing debris that would otherwise be ejected from the armor as a result of the impact of a projectile or missile on the armor. The spall cover of U.S. Pat. No. 6,253,655 also purportedly protects the ceramic or ceramic-based composite armor panels of U.S. Pat. No. 6,253,655 from sustaining damage when dropped onto a concrete surface. In one embodiment, the armor is a laminate including a polymer sheet outer layer, a flexible foam sheet or flexible honeycomb inner layer, a ceramic-based armor plate, and a fiber-reinforced plastic laminate backing. Adhesive layers bond each of the main layers to its adjacent layer or layers. When the armor is accidentally dropped or when an object impacts the polymer sheet outer layer at low velocity, the impact force is distributed by the polymer sheet outer layer to the flexible foam inner layer, which absorbs some of the kinetic energy. When a ballistic projectile such as a bullet strikes the polymer sheet, the projectile perforates the polymer sheet and is defeated by the armor plate. The ceramic layer in the armor literally breaks up the projectile; thus, absorbing a substantial amount of energy from the ballistic projectile. During the ballistic impact event, the ceramic will fracture into small pieces due to the reflective stress wave created by the impact of the ballistic projectile. These small pieces of ceramic are called spall and the flexible foam inner layer and the polymer sheet outer layer keep the resultant spall from ejecting out of the armor.
Canadian Patent No. 2,404,739 and its corresponding U.S. Pat. No. 6,912,944 disclose a ceramic armor system for personnel or vehicles that includes an integral ceramic plate or interconnected ceramic components. The ceramic has a deflecting front surface that includes one or more deflecting nodes. A shock-absorbing layer is bonded to the rear surface of the ceramic plate. The shock-absorbing layer can be formed of a polymer-fiber composite, including aramid fibers, carbon fibers, glass fibers, ceramic fibers, or polyethylene fibers. The shock absorbing layer can include layers of one type of fiber over another type of fiber in a suitable orientation that may be parallel to or at any other angle to one another. A front spall layer can be provided which is bonded to the front of the ceramic plate. The material adhered to the back of the ceramic plate/layer absorbs the residual energy of the ballistic projectile and also protects the wearer from blunt trauma created during the ballistic impact.
In general, ceramic materials used in armor systems are quite rigid and hard, while being relatively low in weight as compared to, for example, steel. Ceramic materials are also relatively resistant to abrasion, heat, chemical reaction and compression. Although substantial protection is provided by currently available body armor including ceramic plates from hits by one or a couple of ballistic projectiles, such body armor often fails upon receiving several more hits by ballistic projectiles.
It is desirable, therefore, to develop improved ballistic resistant devices that reduce or eliminate the above-identified and other problems associated with currently available ballistic resistant devices.